To reduce the fuel consumption amount of vehicles, the engine rotational speed during idling of the engine has been reduced. As a result, the frequency band of engine vibration during idling includes the resonance frequency of the vehicle seat, which reduces the drivability. Seats have been developed that attenuate vibration in the seat front-rear direction by allowing the headrest to pivot with respect to the backrest in the front-rear direction when exciting force is transmitted to the seat.
Patent Document 1 discloses one example of a headrest supporting structure that elastically supports the headrest on the backrest. As shown in FIG. 10, the supporting structure includes brackets 100 provided on the backrest and tubular support members 120 for supporting headrest stays 111, which project from a headrest 110. Each support member 120 is elastically supported on the associated bracket 100 with springs 130, 140 arranged at two different positions in the seat vertical direction. The headrest 110, which is elastically supported by the headrest supporting structure on the backrest, functions as the mass of a dynamic damper, and the springs 130, 140 of the headrest supporting structure function as springs of the dynamic damper.
When exciting force is transmitted to the seat that includes such a headrest supporting structure, each support member 120 tilts about the center of tilting between the springs 130, 140 in the seat vertical direction. The tilting of the support members 120 causes the headrest 110, which is supported on the support members 120 via the headrest stays 111, to tilt with respect to the backrest in the front-rear direction so that vibration of the seat is attenuated.